Dresden 2026 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 21: Phase Transformations II
MM 21.6: Talk
Wednesday, March 11, 2026, 11:45–12:00, SCH/A215
Shear-stress dependent formation of Si-polymorphs during saw dicing analyzed by raman spectroscopy — •Zainab Zainab1,2, Jörg Debus2, and Hannes Kurtze1 — 1Bernburger street 55, 06366 Köthen (Anhalt) — 2August-Schmidt-Str. 4, 44227 Dortmund
Raman spectroscopic analysis of diced silicon wafers reveals that the saw cutting process generates considerable amounts of metastable silicon polymorphs (BC8/R8) along with the original diamond-cubic structure (DC-Si). We demonstrate that the formation of these phases exhibits a distinct spatial distribution that correlates with the shear stress profile imposed by the rotating blade. The DC-Si signal is strongest near the bottom of the cut (wafer tape side), while BC8 and R8 phases are most concentrated near the top surface at the blade entry point. This gradient arises from differences in the mechanical stress state: at the top, the steeper blade angle generates substantial shear stress in addition to normal compressive stress, facilitating shear-induced phase transformation at locally applied pressures. At the bottom, the nearly parallel blade trajectory produces predominantly normal stress with minimal shear, suppressing the formation of metastable phases. Additionally, we find that specific feed rates enhance phase transformations and intensify the spatial gradient. These findings confirm that shear stress is the critical enabling factor for polymorph formation during mechanical processing of silicon, consistent with recent studies showing dramatic reduction in transformation pressures under non-hydrostatic conditions.
Keywords: Shear stress; Raman spectroscopy; Topological profiles; Saw dicing; Phase transformations